Association of Weight Status With Mortality in Adults With Incident Diabetes

Study Questions:

Is weight associated with mortality among adults with new-onset diabetes?

Methods:

This is a pooled analysis of five longitudinal cohort studies including the Atherosclerosis Risk in Communities (ARIC) study, 1990-2006; Cardiovascular Health Study (CHS),1992-2008; Coronary Artery Risk Development in Young Adults (CARDIA) study, 1987-2011; Framingham Offspring Study, 1979-2007; and Multi-Ethnic Study of Atherosclerosis (MESA), 2002-2011. Participants over the age of 40 years with incident diabetes (defined as fasting glucose 126 mg/dl or greater or newly initiated diabetes medication) were included. Participants were classified as normal weight if their body mass index (BMI) was 18.5-24.99 or overweight/obese if BMI was 25 or greater. The primary outcome measures were total, cardiovascular, and noncardiovascular mortality.

Results:

A total of 2,635 participants contributed 27,125 person-years of follow-up. The proportion of adults who were normal weight at the time of incident diabetes ranged from 9% to 21% (overall 12%). During follow-up, 449 participants died: 178 from cardiovascular causes and 253 from noncardiovascular causes (18 were not classified). The rates of total, cardiovascular, and noncardiovascular mortality were higher in normal-weight participants (284.8, 99.8, and 198.1 per 10,000 person-years, respectively) than in overweight/obese participants (152.1, 67.8, and 87.9 per 10,000 person-years, respectively). Risk of adverse events was higher among normal-weight participants who developed diabetes compared to overweight/obese participants with diabetes, including a hazard ratio (HR) of 2.08 (95% confidence interval [CI], 1.52-2.85) for total mortality, HR of 1.52 (95% CI, 0.89-2.58) for cardiovascular mortality, and 2.32 (95% CI, 1.55-3.48) for noncardiovascular mortality, after adjustment for demographic characteristics and blood pressure, lipid levels, waist circumference, and smoking status.

Conclusions:

The investigators concluded that adults who were normal weight at the time of incident diabetes had higher mortality than adults who were overweight or obese.

Perspective:

As the authors point out, these results are somewhat surprising, particularly for cardiovascular mortality. Lower body weight may be an indicator of health, but also may be the result of subacute disease processes, thus an indicator of poor health. Repeat measures of body mass across the lifespan would help to tease out this process.